We use VA Hashtags fairly widely here. Some common patterns have emerged with our developers, but they clutter the VA Hashtags view. I was just reading the latest release notes and the mention of "Rules for hiding VA Hashtags..." reminded me of something one of our guys here mentioned:
While we can hide a specific tag, he wondered about hiding tags that match a pattern e.g. #ABC* to match #ABC12345 and #ABC09876. Perhaps even regular expression support too, though wildcards would suit us well initially.
This makes a lot of sense, and I have put in a feature request for this to see what our developers make of it:
case=118279
For now, are you aware that you can hide hashtags by file, directory and project? This offers another way of limiting the tags that are being shown, but I don't know how helpful this will be for you.
Also note that the hashtag toolwindow supports negative filtering. You could put -abc in the edit control at the top of the window. It is a static field whose content persists after restart.